The aim of this project is to develop chemically designed 3D graphene architectures with the objectives to favor the intercalation of both cations such as Li+, Na+, but also Ca2+, Mg2+ and Al3+, and/or anions (PF6-, BF4-, TFSI) in batteries or dual cells by controlling the interlayer distance between the assembled graphene sheets. The new materials, obtained after the reduction of graphene oxide sheets cross-linked using either organic pillars with selected lengths or new aerogel formation techniques, will display different intercalation sites dimensions, optimized passivation and porosity. Multidimensional electron transport pathways and minimized ions transport distances between bulk electrodes and electrolyte will thus be favored. These scaffolds will be used in innovative dual electrochemical cells configuration operating following an intermediate and reversible process between batteries and supercapacitors with the expectations to improve energy/power densities compared to actual electrochemical storage devices.

The PV sector is experiencing a fast growth and is becoming one of the main pillars for the energy transition. The goal of 30% efficiency (challenging roadmap issued during COP21, initiated by IPVF and named “30-30-30”) will be extremely difficult to reach with classical solar cells based on single junctions. On contrary, tandem cells could reach 43% theoretically by combining a VIS/NIR bottom cell, Si-made, with a top cell collecting the blue/UV range of the solar spectrum, which could be a CIGS top cell specially optimized with a bandgap about 1.7 eV. We propose a new and disruptive approach based on using wideband gap III-V (GaP-based) buffer layers between Si and CIGS. We expect that epitaxial (CIGS/III-V/Si substrate) developed in this project will reach 18% at 1.7 eV. Original designs of (CIGS/III-V/Si/Si substrate) tandem cells with two terminals and a efficiency of 25% are proposed at the end of the project.

The recent rise of high-resolution and depth imaging techniques like photoacoustic microscopy (PA) stimulates novel research areas in biology. In vivo tracking of immune cells, signaling inflammation and severe pathologies thereof, is one of them and attracts great interest. The AZOTICS project thus aims at addressing the current PA microscopy limitations by fabricating innovative biocompatible elastomeric nanolabels relying on azo photochromes. Photostimulated actuation mechanisms will help amplify the PA contrast based on thermal expansion. The photoinduced mechanical deformations of single nano-objects will be assessed at the nanoscale using atomic force microscopy in order to propose a rationale for the performance of photoacoustic probes beyond their sole optical absorption ability. Their PA imaging capability will be validated through an in vitro, in cellulo and in vivo continuum of studies involving macrophage staining, microfluidic systems mimicking microvasculature, and models of acute inflammatory activated in mice. The interdisciplinary AZOTICS consortium gathers experts in chemistry, physics and optics from Nantes and Grenoble, having already tightly worked together and being keen to share their knowledge in order not only to address unexplored fundamental questions but also to propose innovative photoacoustic systems for in vivo imaging.

Photo-induced phase transitions, driven by an intense optical pulse, allow for ultrafast control of the physical properties of materials by light (2 eV range). However, heat dissipation and temperature rise limit the control of coherent atomic motions and functions, therefore other means to drive materials with lower photon energy are required. In addition, the direct activation by light of soft lattice modes that drive phase transitions through lattice instability is not always possible, because of the optically inaccessible frequency range and/or because of the symmetry of the modes precluding optical transitions. Here we propose to explore the fascinating possibilities offered by Non-Linear Phononics (NLP) to control functional molecular materials. NLP takes advantage of strong infrared excitation (0.2 eV range) for driving a large amplitude high-frequency polar mode QIR, which can couple through nonlinear (anharmonic) terms and activate those "soft modes" able to drive phase transition. The time average creates an “effective” dynamic potential, rectifying the phonon field and adiabatically directing a slow mode, which may significantly change the average atomic positions to create a new phase of different structural and electronic orders. This process occurs abruptly, on the timescale of a phonon period. Ultimately, it appears possible to drive a symmetry breaking towards a more ordered state, allowing to revisit the old adage “structure makes function”. Up to now, this new opportunity is only just emerging, and has essentially been employed only on a few inorganic materials. In view of tantalising theoretical predictions, experimental opportunity, and the available technology suiting the challenge, we propose to develop nonlinear phononics for controlling electronic phase transitions in molecular materials. Importantly, the latter are rich resources of different functionalities. They present unique instabilities of molecular electronic states (charge, spin, …) that are strongly coupled to structural distortions of both the soft molecules and the soft lattice, and as such they are fitting test bed candidates for exploring NLP concepts in condensed matter. Our approach that consists in mixing experimental and theoretical expertise in material science seems an effective and attractive strategy in view of different types of coupling and different physical processes behind NLP driven phase transitions. ELECTROPHONE will benefit from the expertise of the different partners, as developing this challenging project will require detailed knowledge of crystalline structure, phonons and symmetry, theoretical calculations of intra- and inter-molecular modes, description of their couplings, as well as time-resolved experiments on the ultrafast time-scale. The ultimate goal of this project consists in recasting a new physical picture of Non-Linear Phononics in electronic phase transition materials by networking experimentalists and theorists.

RENOIR will develop intense broadband deep-red (650 – 800 nm) 1D sources based on a Mo6@PDMS nanocomposite made of original Mo6 photoluminescent clusters dispersed in PDMS (polydimethylsiloxane) polymer matrix. The nanocomposite will be obtained by copolymerization of a homogeneous solution -with controlled viscosity- containing monomers and functional clusters. It will be elaborated by a team of chemists recognized in the synthesis of emitting nanomaterials based on a metal atom cluster. Nanometer sized metal clusters (< 2 nm) also called “nanoclusters”, which consist of less than a few dozens of metal atoms such as Au, Ag, Pd, Pt, Cu, Mo, Ta, Re, could be defined as an in-between atom and nanoparticle. These nanoclusters have attracted more and more attention due to their unique electronic structures and the subsequent unusual physical and chemical properties. Compared to other luminophors, such cluster units have several advantages and in particular unique optical features: a high quantum yield in solid polymer matrix, a large Stokes shift and no photobleaching or photoblinking compared to organic dyes or QD’s. Moreover, we have already shown that such luminescent pigments can be incorporated in various matrices like silica nanoparticules or copolymers for applications ranging from biolabelling to lighting and displays. As preliminary results of RENOIR, micronic waveguides and nanotubes were obtained from a nanocomposite photoresist based on the embedding of Mo6 clusters in a SU8 photoresist, subsequntly patterned by classical UV lithography and wetting template method respectively. The change of host matrix here is challenging and will enable a significant increase in delivered power since the quantum yield of the clusters in PDMS is 5 times higher than in SU8. RENOIR is built on the complementary expertise and know-how of three teams mixing chemists and physicists. It is divided in 3 work packages (i) optimization of chemical composition and deep-red luminescence properties of Mo6@PDMS nanocomposite, (ii) optimization of molding technique for designing Mo6@PDMS 1D-structures and (iii) integration of the Mo6@PDMS 1D-structures on a photonic chip: design and characterizations. The patterning and characterization of the 1D micro- and nano-sources performed by the two other teams (physicists and opticians). Low cost molding technology specific to polymer host material manipulated in liquid phase will enable easy, low-cost and ecologically-friendly fabrication. That will be possible thanks to the collaboration with the PERFOS R&D platform localized in Lannion which is specialist in custom microstructured fibers fabrication (www.perfos.com). PERFOS R&D platform will supply centimeters-long samples of microstructured fibers with hole diameters ranging between 5 µm down to hundreds of nm. Finally, two optical pumping solutions will be tested in order to get integrated intense large deep-red emitting sources with applications in lighting and data communications.